Sheldon: Leonard, you may be right. It appears that Penny secretly wants you in her life in a very intimate and carnal fashion.
Leonard: You really think so?
Sheldon: Of course not. Even in my sleep-deprived state, I’ve managed to pull off another one of my classic pranks. BAZINGA!

Leonard: For God’s sake, Sheldon, do I have to hold up a sarcasm sign every time I open my mouth?
Sheldon (intrigued): You have a sarcasm sign?

Sheldon: She calls me moon-pie because I’m nummy-nummy and she could eat me up!

Sheldon: What exactly does that expression mean, ‘friends with benefits?’ Does he provide her with health insurance?

Leonard: I’m just saying, you catch more flies with honey then with vinegar.
Sheldon: You catch even more with manure, what’s your point?

Sheldon: I think that you [Leonard] have as much of a chance of having a sexual relationship with Penny as the Hubble telescope does of discovering at the center of every black hole is a little man with a flashlight searching for a circuit breaker.

Sheldon: There’s a fine line between wrong and visionary. Unfortunately, you have to be a visionary to see it.

Sheldon: Oh Mario … if only I could control everyone the way I control you … HOP! YOU LITTLE PLUMBER! HOP! HOP! HOP!

Sheldon: Hello, I know you’re out there. I can hear you metabolizing oxygen and expelling carbon dioxide.